Pasteurizing control system



April 3, 1951 2 Sheets-Sheet 1 Filed Aug. 7, 1948 Y R m 5 M m H mmkwfi m wN O t W w w I R pr. B v k m L w w EH50 v3.2 l1 SNEBEE LA Q 8 on cc H Y B N .532. :45 EE oh Nh April 3, 1951 v C. F. ALDRIDGE ET AL PASTEURIZING CONTROL SYSTEM 2 Sheets-Sheet 2 Filed Aug. 7, 1948 R m m m 2 om 0P 2 0k owmmfimm 8105.? mm

CLARENCE F. ALDRIDGE BY CARL L. BROWN ATTORNEY Patented Apr. 3, 1951 UNITED STATES PAETENT OF E EC lPASTEUREZIF-IG CQNTROL' SZYSFIEM Clarence F. Aldridge and Carlll. Brown, Rochester, N. Y., assignors to Taylorinstrument Companies, Rochester, N. Y.

New York a-- corporation of- This invention relatesco a pasteurizing system and to: a differential switch for use therein.

In the pasteurization or" a" liquid such as milk or the like, it is customary to cause the liquid; after it has been pasteurized, to flow through a regenerator in heat exchange relation to some of the'flowin unpasteurized liquid. so that'a portion of the heat in the pasteurized liquid can be recovered. If a leak develops inthe' regenerator of the present apparatus it is possible; under certain pressure'conditions, forthe unpasteurized liquid to'leak into'the 'pasteurized'liquid with the resultant contamination In accordance with the present invention there is provided a. pasteurizing system in which the pasteurized liquid is normally maintained at a higherpressure thepressureof the unpasteurized liquid in heat exchange relation therewith so that any leakage will'be from the pasteurized' liquid to the unpasteurized liquid and not'vice versa; However, if'this normal pressure condition becomes reversed, provision is made for Stoppingthe flow ofat least one of said liquids and for preventing the resumption of flow until the ioperator'starts it after the required pressure conditions have been satisfied.

The various features and advantages of the invention will-appear from-the-detailed description and claim when taken with the d'rawingin which Fig. l is a diagrammatic showing of a pasteurizing system in accordance with the present invention; Fig. 2' is a longitudinal section through a diiierentia'i switching unit which is incorporated inthe system of Fig: l and'which formsapart of-the present invention; and Fig; 3 is a detailed view of a" portion of the switching unit; partiallybroken awayshowing the micro switchand its mounting.

The present invention-is intended-for use in a pasteurizing system more completely disclosed in Patent 2,472,984of3aymond Olson; granted June 14; 1949, and'is an improvement in the invention disclosed in-Patent 2,455,605 offtaymond E. Olson, granted December 7, 1948-. In thatsystem there is employed-a combined pasteurizing unit a regenerating unit 5', and a cooling unit 2; In the pasteurizing unit the milk 01'' other liquid tobe pasteurized flows through a set of coil'sor passages a in heat exchange relation to a set of heatin coils or-passages'fi through which there is recirculat d Watermaintained at a temperatureslightly above the pasteurizing temperature.

The regenerating unite-includes two passageways ill and H in heat exchange relation toeach other. The raw milk'from' the tank !2 is pumped by a so-call'ed booster pump i3 (which may be oi'the centrifugal type) through the passageway iii and by the timingpump. i l (which'i preferably of the positive type) through the'passageway, B'of the pasteurizer; The milk leaving the pas teurizer passageway 6' passes intoa suitable holding tube through which it" travels for the" required fifteen second holding interval required in so-called short time pasteurization andthen flows through the flow diversion valve FD'through' the passageway H of-the regenerator. Thu the regenerator conducts thepasteurizin milkfrom. the past'eurizer in heatexchange relation tothe' raw milk in the passageway 59 thereby serving to cool. the pasteurized milk and to heat partially the incoming raw milk. the passageway H of the regenerator 5, the pasteurized milk flows through the cooling unit l to the discharge pipe i5.

If; however, the milk has not been heated to the proper temperature in passageway 8, suitable means, to be described, operates the flow diversion valve Fl'lgto'divert the improperly processed milkthrough a pipe 56 to the tank l2? so that this milk'can be reprocessed. The two passageways it: and ,I 5 through the regenerat'or, are.n0r.-' mally defined by a series of 'plates that'can be readily taken apart and reassembled daily. for purposes of cleaning. In view of'thi construction it is possible; on rare occasions, for the milk in one passage to leak into theother passage especially if the raw milk under a higher pressure than the pasteurized miik in the other pas.- sage, then the pasteurized milkv will becom contaminated;

In accordance with the present invention, pro.- vision is. made for insuring thatthe pasteurized mil: in the regenerator will always be at a higher pressure thanthe raw milk in the regenerating unit so that" any. leakage in the regenerator will be from the pasteurized milk to the raw milk. If however, this desired pressure relation becomes reversed,.there is provided a differential pressure unit'which. will immediately function with related control mechanism to stop. the flow of milk through one or. both passages .in the regenerator. For this purpose there. is provided a sanitary differential pressure ,unit P, including a T-shaped fitting l3 havingrits opposing ends respectively sealed by the flexible corrugated diaphragms l9 and 2'6, which are backed by suitable protective stops 19a andflZGdKFig. 2). A'. branch pipe 2| which is connected to theinlet of the passageway Idapplies, thev pressure of the. rawmilk. to. the

upper surface of the diaphragm 29 (Fig. 1). Similarly, the branch pipe 22 which is connected to the outlet of the pasteurized milk passageway ll, applies the pressure of the pasteurized milk to the lower surface of the diaphragm it. A rod 23 has one of its ends secured at the inner surface of the diaphragm H9. The other end of the rod 23 is provided with an adjustable telescopic extension 23a which normally just rests against diaphragm 2B. It should be mentioned that the last-mentioned end of rod .23 is not attached to diaphragm Zli. This rod has a bracket 28 secured thereto at a point opposite the side opening 29 in the fitting IS, A switching unit generally designated S (Fig. 3), includes a micro-switch 30 which has its actuating button 3i supported in a position to cooperate with the free end of the bracket 28.

The switch S comprises an annular plate 32 having its outer margin adapted to be sealed to the fitting in the opening 2%. The plate carries a projecting support 3%. The support has pivoted thereon at 3 5, a lever 36 on the lower end of which the micro-switch 353 is supported. The lever 36 is pivotally mounted so that the button 3i of the micro-switch 30 can be swung toward or away from the bracket 23 in order to select the pressure value at which the micro-switch will be operated. The swinging adjustment of the lever 36 may be effected in any well-known manner. As herein illustrated, this adjustment is effected by a flange 38 on the outer end of the lever 36 and a cooperating flange 39 on the outer end of the support 34, both flanges being in parallel planes which are also parallel to the principal yr The plate 32 also has secured thereto the support 32 which projects therefrom in a direction parallel to the support 34. The support Q2 terminates at its outer end in an angular flange Q3 (Fig. 2). This flange carries the conductors it leading to the micro-switch 36, and also tightly holds the rim of a cuplike closure iii in sealed relation with the plate 32.

In the operation of the system, it will be assumed that there is a source of hot water for heating the pasteurizer and that there is a source of cooling water or brine for circulation through the cooler I. The attendant then closes the sustained contact switch 48 whereupon a circuit is completed from one side of the current source, conductors 59 and 5!, winding of the solenoid 52, switch 49, conductor 53, armature 5d and back contact of solenoid 55, conductor 55, switch iii in the position illustrated, since it is assumed that the flow diversion valve is in its diverted position, conductors 58, 59 and B8 to the other side of the current source. The solenoid 52 is energized in this circuit and completes an operating circuit to the motor of the timing pump it. Pump l4 operates to draw the milk through the passage" way l0. At the same time that the solenoid 52 is operated to start the pump it, the red lamp 6i is lighted to indicate that the flow diversion valve is in its diverted position. Lamp ii is lighted from one side of the current source, conductors 6!], 59, and 58, switch 57 in the position illustrated,

lamp 6i, conductors 63 and to the other side of the current source.

When the temperature of the milk discharged from the holding tube H is at the required pasteurizing temperature, the bulb 65 of the thermosensitive tube system including the capillary tube 66 and the Bourdon spring ET is actuated to swing the blade 69 of the thermal switch into engagement with the contact i0. In response to this action, the flow diversion valve PD is moved to its forward flow position as a result of the completion of the following circuits. As soon as the movable blade 69 engages the fixed contact iii of the thermal switch, a circuit is completed for energizing the solenoid ii. This circuit extends from one side of the current source, conductor so, winding of the solenoid ll, conductor l2, switch contacts 69 V and it, conductor 73, resistor i l, conductor 50 dil to the other side of the current source. The solenoid ii is energized in this circuit and locks itself operated independently or" the thermal switch contacts til and iii, in a circuit now traced from the conductor Ell, winding of the solenoid ll, its armature l5 and front contact, resistor i i, conductor 5E] to the other side of the current source. erated, it closes an energizing circuit for the solenoid 55. This circuit extends from one side of the current source, conductor 69, front contact and armature it of solenoid ll, winding of the solenoid 55, conductor 59 to the other side of the current source. With the solenoid 55 0perated, a circuit is completed for the solenoid ll of the electro-pneumatic valve 58. This valve supplies compressed air through the pipe "F9 to the motor of the flow diversion valve FD, causing this valve to position its movable element in a forward flow position. As this valve assumes its new position, switch El is moved to its right hand position for a purpose to be described. The energizing circuit for the solenoid ll of the electro-pneumatic valve i8 is traceable from one side of the current source, conductor 66, armature 8G and front contact of solenoid 55, conductor 8i, winding of the solenoid'l'l, conductors 82 and 50 to the other side of the current source. When the solenoid ll is energized, it applies compressed air through the pipe 79 to the motor of the flow diversion valve as previously referred to. When the switch Ell is moved to its right hand position, as just mentioned, the green lamp 83 is lighted to indicate that the flow diversion valve is in its forward flow position. The green lamp 83 is lighted in a circuit extending from one side of the current source conductors 5t and $3, lamp 83, conductor 85, switch at, conductors 58, 5s and $0 to the other side of the current source.

The attendant now closes the toggle switch 98 and momentarily depresses the button 9] which completes a circuit for latch solenoid 93 from one side 56 of the current source, conductor 63, contacts of button 9|, winding of solenoid 93, conductors 59 and 66 to the other side of the current source. Solenoid 93 closes its contacts and causes its latch 9 to engage the catch 95 of the catch solenoid 95 so that solenoid 93 is latched in its closed position until it is released by the operation of catch solenoid 96. In accordance with this invention, the catch solenoid t is shunted as long as the switch 35 is in its closed position, that is, while the pressure of the pasteurized milk in the regenerator is greater than the pressure of the raw milk in regenerat- As soon as the solenoid ll is oping heat exchange relation therewith. Also, when the solenoid 55 is operated, the relay 8! is energized to complete a break point in the circuit of the relay 88 which connects the power leads to the motor 89. Motor 89 drives the centrifugal type booster pump [3 which advances the raw milk from the storage tank I2 through the regenerator 6.

In the event that the pressure of the pasteurized milk in the regenerator drops below the pressure of the raw milk in the regenerator, the switch P will open its contacts. This opens the short circuit around the winding of the catch solenoid 96 causing it to energize. Solenoid 96 on operating, withdraws its catch 95 from the latch 96 of latch solenoid 93 which releases. Solenoid 93, on releasing, opens the operating circuit of relay 88 which releases to open the operating circuit of pump motor 89, thereby stopping the pump [3. Thus raw pasteurized milk under abnormal pressure will not be advanced through the regenerator.

It should be pointed out that the latch solenoid 93 cannot be latched in it operated position until the manual button 9| has been depressed and until the pressure of the pasteurized milk in the regenerator is greater than the pressure of the raw milk therein so that the switch P will be closed. Thus, if this required pressure relation does not prevail, the depression of button 91 will be inefiective. While the latch solenoid 93 will be operated under the assumed condition during the depression of button 9|, the catch solenoid 96 will be operated, since the switch so will be open to remove the shunt circuit about the winding of this solenoid.

It will be understood that low pressure or vacuum on the upperside of diaphragm (Fig. 1) will not operate the switch P since the rod 23 and its extension 23a are not attached to diaphragm 20. Thus abnormally low pressure in the raw milk passage ID will not operate the switch P to permit the flow of pasteurized milk under abnormal pressure conditions.

What we claim is:

In a pasteurizing system, a heating unit provided with a primary passage for a heating liquid and with a secondary passage for a liquid to be heated, said passages being in heat exchange relation with each other, means for causing said heating liquid to flow through said primary passage at a given pressure, means including an electrically operated pump and a circuit therefor for causing the liquid to be heated to flow through said secondary passage at a pressure normally lower than said given pressure, and a differential pressure switch controlling said circuit and responsive to a change in the normal pressure relation between the liquids in said passages for stopping said pump, said differential pressure switch comprising a T-shape fitting provided with a side opening and with two opposed end openings, a flexible diaphragm sealing each of said end openings, a rod within said fitting having one of its ends secured to the inner surface of a first one of said diaphragms and having its other end in contact relation with the second of said diaphragms so that it is free to move relatively thereto, switch contact operable at said side opening and means movabl by said rod for actuating said switch contacts, said fitting being connected in said system with said first diaphragm exposed to the pressure of liquid in said primary passage and with the second diaphragm exposed to pressure of the liquid in said secondary passage.

CLARENCE F. ALDRIDGE. CARL L. BROWN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 457,572 Bergmann Aug. 11, 1891 936,329 Lacke Oct. 12, 1909 1,946,412 Rowley Feb. 6, 1934 2,094,319 Faust Sept. 28, 1937 2,204,644 Adams June 18, 1940 2,414,623 Wildermuth Jan. 21, 1947 2,455,605 Olson Dec. 7, 1948 

